﻿using System;
using System.Collections.Generic;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Web;

public class KeyPwd
{

    private SymmetricAlgorithm mobjCryptoService;
    private string Key;
    /// <summary>
    /// 对称加密类的构造函数
    /// </summary>
    public KeyPwd()
    {
        mobjCryptoService = new RijndaelManaged();
        Key = "1@#^fdssd345+)8*sdfswdssda+";
    }
    /// <summary>
    /// 获得密钥
    /// </summary>
    /// <returns>密钥</returns>
    private byte[] GetLegalKey()
    {
        string sTemp = Key;
        mobjCryptoService.GenerateKey();
        byte[] bytTemp = mobjCryptoService.Key;
        int KeyLength = bytTemp.Length;
        if (sTemp.Length > KeyLength)
            sTemp = sTemp.Substring(0, KeyLength);
        else if (sTemp.Length < KeyLength)
            sTemp = sTemp.PadRight(KeyLength, ' ');
        return ASCIIEncoding.ASCII.GetBytes(sTemp);
    }
    /// <summary>
    /// 获得初始向量IV
    /// </summary>
    /// <returns>初试向量IV</returns>
    private byte[] GetLegalIV()
    {
        string sTemp = "E4ghj*Ghg!rNIfb&95G86GfghU#er57HBh(u%g6HJ($jhWk7!hg4ui%$hjk";
        mobjCryptoService.GenerateIV();
        byte[] bytTemp = mobjCryptoService.IV;
        int IVLength = bytTemp.Length;
        if (sTemp.Length > IVLength)
            sTemp = sTemp.Substring(0, IVLength);
        else if (sTemp.Length < IVLength)
            sTemp = sTemp.PadRight(IVLength, ' ');
        return ASCIIEncoding.ASCII.GetBytes(sTemp);
    }
    /// <summary>
    /// 加密方法
    /// </summary>
    /// <param name="Source">待加密的串</param>
    /// <returns>经过加密的串</returns>
    public string Encrypto(string Source)
    {
        byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);
        MemoryStream ms = new MemoryStream();
        mobjCryptoService.Key = GetLegalKey();
        mobjCryptoService.IV = GetLegalIV();
        ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor();
        CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
        cs.Write(bytIn, 0, bytIn.Length);
        cs.FlushFinalBlock();
        ms.Close();
        byte[] bytOut = ms.ToArray();
        return Convert.ToBase64String(bytOut);
    }
    /// <summary>
    /// 解密方法
    /// </summary>
    /// <param name="Source">待解密的串</param>
    /// <returns>经过解密的串</returns>
    public string Decrypto(string Source)
    {
        try
        {
            byte[] bytIn = Convert.FromBase64String(Source);
            MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
            mobjCryptoService.Key = GetLegalKey();
            mobjCryptoService.IV = GetLegalIV();
            ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();
            CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
            StreamReader sr = new StreamReader(cs);
            return sr.ReadToEnd();
        }
        catch
        {
            return string.Empty;
        }
    }
}